Integrated Pest Management

B.C. Pest Monitor — Former Newsletter of IPM in British Columbia

Vol. 2 No. 2 November 1993

Tree and Ornamental Disease Control in the City of Victoria

Michelle Gorman, Ph.D.

Integrated Pest Management Coordinator, Victoria Parks and Recreation Department

Plant life in the Victoria region reflects the mild, moist winters and relatively dry summers. It is because of this climate that residents of Greater Victoria enjoy a wealth of magnificent native and exotic trees. While trees and ornamental plantings are appreciated for their aesthetic beauty and environmental qualities, they also make a statement about the health and spirit of a community. Keeping these plantings healthy is a dynamic process that reflects the legal, ecological, sociological, aesthetic and other considerations of the community.

Integrated pest management (IPM) programs being implemented for plant disease control within the City of Victoria Parks system coordinate expertise in horticulture, landscape and architectural design, arboriculture and pest control. Victoria's approach is to develop procedures that increase plant vigour (to allow plant material to better withstand disease infection) and use the natural control forces in the environment to reduce the disease inoculum (the parts of the pathogen that causes the disease). Key elements in Victoria's approach to disease control are:

1. Improve Plant Vigour
   • select the correct plant material for the site
   • plant at the proper depth with correct planting area for root ball
   • provide proper irrigation and drainage
   • stake correctly when needed and prune appropriately
   • apply fertilizers and growth regulators carefully and judiciously
   • give trees and large ornamental plantings enough space to grow
   • avoid disturbing plant roots during construction; take steps to increase root production if roots are damaged
   • avoid treatments that destroy the plant's defense systems or cause internal injuries
   • avoid wounding trees with machinery such as mowers and weed-eaters
2. Manipulate the Environment to Reduce Spread of Disease
   • increase air flow around plants as appropriate
   • manipulate air humidity levels
   • avoid disease by using resistant or tolerant varieties
   • decrease infection of susceptible varieties by understanding the disease life cycle and manipulating factors to avoid the problem
   • destroy and remove diseased tissue and overwintering stages of the disease
   • inspect plants for insect and disease problems and conformation to horticultural specifications prior to purchase
   • avoid planting large areas of the city with one plant type to decrease the risk of severe loss to one disease
   • isolate or remove diseased stock, when appropriate, to avoid spreading diseases such as Verticillium wilt, Pseudomonas, etc.
   • use parasitic or competing biological agents to control pathogens
   • use preventive treatments, such as lime sulphur, anti-transpirants and fixed copper or bordeaux applications on nursery stock and plant material known to have problems with certain diseases every year.

Two main procedures have been established:

1. Selecting Tree Whips
   
   This year, Yvan Caron (Deputy Superintendent Horticulture) coordinated a committee to develop a tree planting philosophy and to select approximately 30 types of tree whips suited to Victoria's unique environmental conditions. Among the criteria considered were the tree's ability to withstand fluctuations from cool, wet winters to hot, dry summers, pollutants (such as carbon monoxide and road salt), wind and salt spray. Also considered were adaptation to soil conditions and drainage, height and width characteristics, and disease and other pest resistance.
   
   
2. Establishing the Right Site
   
   
   The Victoria Park Design and Development Department works with the city planners, the community and various parks departments such as Small Parks, Horticulture, Repair and Maintenance to prepare planting sites in advance. By providing appropriate irrigation, drainage, and placement of trees they help ensure healthy, vigorous plants.

Common Diseases of Ornamentals and Their Management

Hawthorn Leaf Blight

Causal organism: Entomosporium mespili (fungus)

Hawthorns, mountain ash and serviceberry are susceptible to leaf blight caused by this fungus.

Significance in Victoria:

Hawthorns comprise approximately 11% of the boulevard trees, with 1,883 trees listed in the city inventory. The disease does not normally kill the trees but makes them appear sparse and unhealthy; this has prompted some residents to ask that their hawthorns be removed and replaced with other trees.

Disease symptoms / cycle:

Small spots appear on leaves beginning in May; they develop to obvious large, light reddish or dark brown blotches by mid-summer. Affected leaves dry out and drop prematurely, resulting in defoliation of 1/3 to 2/3 of the trees' leaves. Although the disease life cycle is generally understood, the conditions influencing disease expression are not well understood. Further research is needed to find out if there is a relationship between the disease and insects, such as aphids and leaf hoppers.

Control options:

• Trees may be able to outgrow the disease. Trees along streets that had a past history of severe leaf drop (4-6 years ago) were in very good condition this year and seem to have outgrown the disease. Trees will continue to be monitored to verify this observation.
• Watering and fertilizing seemed to help trees to withstand disease.
• No true resistance to the disease has been observed but tolerance may be a possibility.

Phytophthora Root Rot of Lawson Cypress and Other Conifers

Causal organism: Phytophthora lateralis (Fungus)

Significance in Victoria:

P. lateralis is a very destructive root pathogen of Lawson cypress in ornamental plantings. Although they make up less than 1% of Victoria's boulevard trees, the 106 Lawson cypress in the city are highly valued for the dignity and character they contribute to the areas where they are planted.

Disease Symptoms / Cycle:

Symptoms begin as a slight chlorosis of leaves throughout the tree, progressing to further chlorosis, with occasional areas of dead tissue progressing to death of the tree. The fungus overwinters in infected roots and also in the soil; during cool, wet weather the disease spreads more quickly. The fungus survives during hot, dry weather and very cold weather and starts infections again when conditions are favourable.

Control Options:

• Control of Phytophthora root rots has been restricted to planting resistant varieties, when available, with some control provided by systemic fungicides.
• Phytophthora spp. have been controlled well by some biological control organisms under laboratory conditions. In cooperation with Agriculture Canada, Victoria is testing a naturally occurring species of bacterial that competes with the disease organism and produces an antibiotic that kills the fungus. (Experimental work is also being conducted in Vancouver for the same problem).

Bacterial Canker and Gummosis of Ornamental Fruit Trees

Causal Organism: Pseudomonas spp (Bacteria).

Also known as bud blast, blossom blast, dieback, spur blight and twig blight, this affects stone fruits, pears, citrus, lilacs, roses, and many annual and perennial ornamentals.

Significance in Victoria:

The disease has been present in Victoria for decades. Due to the past history of the disease in the area, certain types of ornamental plantings, particularly pears, were avoided.

Disease Symptoms / Cycle:

Bacteria enter limbs through bases of infected buds or spurs, pruning cuts, leaf scars and injuries; infection of limbs occurs in fall and winter. Cankers develop on branches and main trunks, which kills young trees and reduces the yield, or kills, older trees. Cankers develop rapidly in fall after trees have become dormant and before onset of low temperatures; canker development is slow during cold winter weather with growth increasing in spring.

Control Options:

• Avoid susceptible varieties and use only healthy nursery trees for park plantings. Pyrus calleryana var. `Chanticleer' is reported as resistant or very tolerant, however experience has shown that up to 1/3 of this cultivar can be lost to this disease. Therefore even "tolerant" varieties are tested in the nursery for 2-3 years prior to planting out.
• Prune out diseased tissue (disinfecting tools between cuts) well below canker.
• Apply fixed copper in fall and spring to susceptible stock.
• Prune and spray on dry days, preferably in the morning, to allow wounds or sprays to dry.

Nectria Cankers of Maples

Causal Organism: Nectria spp. (Fungus)

Significance in Victoria:

Losses are greatest in young trees due to girdling of the trunk or scaffold branches.

Disease Symptoms / Cycle:

Early cankers are small, circular, brown areas with the central area becoming sunken and black while the edges are raised above the healthy bark with age. Cankers usually develop around bud scars, wounds, twig stubs or in crotches of limbs. The fruiting bodies of the fungus are white, creamy-yellow or bright orange.

Control Options:

• Acer truncata var. Pacific Sunset seems affected more than the others, therefore should be avoided.
• Maintain trees in a vigorous condition in spring by fertilizing and watering.
• Prune out and destroy tissue with fruiting bodies or cankers.
• Apply a long-lasting protectant fungicide (Bordeaux or Captafol) immediately after leaf fall.

Phytophthora Root Rot of Rhododendrons and Azaleas

Casual Organism: Phytophthora spp. (Fungus)

Significance in Victoria:

Much of the present Beacon Hill Park Nursery is built upon previous swamp land, having wet heavy soil conducive to Phytophthora build up.

Disease Symptoms / Cycle:

This is a seedling or nursery disease that chiefly affects plants up to 2-3 years old. The fungus prefers cool situations and soil that is not acidic enough for good rhododendron growth. Leaves become chlorotic, roll downward parallel to the midrib and eventually wilt. The cambium tissues turn a dark brown with discoloration coming later to phloem and xylem tissue and the root tissue dies.

Control Options:

• Switching to a soil-less mix in containers at the Beacon Hill nursery has decreased the incidence of Phytophthora; generally root rot in nursery rhododendrons is no longer a problem.
• Phytophthora of rhododendrons and azaleas is still a problem in perennial beds. The disease develops within a year of planting out from the nursery, usually as a result of poor site selection and preparation, including insufficient drainage.
• It has been observed that the small-leaved varieties of rhododendrons, such as 'Yellow Hammer' are more prone to Phytophthora infection.

Turf Disease Control Through Integrated Turf Management

Leslie MacDonald Plant Pathologist, BC Ministry of Agriculture, Fisheries & Foods

The goal in turf management is to provide healthy turfgrass to the end user. Healthy turf grass has adequate root and foliage growth that withstands stress and, ultimately, invasion from fungal pathogens. Healthy, vigorous plants have active defense mechanisms. This enables them to restrict the invasion of fungi through processes such as increased lignification of the plant tissues.

One of the greatest changes that would reduce turf stress is to raise the mowing height of greens. Ideally, good turf management practices include increasing cutting heights and not allowing traffic on the turf during wet conditions, but these factors are often out of the manager's control. In reality, turf is exposed to many stresses, such as short mowing, heavy traffic, year-round playing, periods of prolonged wet weather, temperature extremes and the non-target effects of pesticides. This makes it essential to give careful attention to those management practices one has control over, such as fertilizing, fungicide use, watering, and aeration. The challenge is to understand the effects of management practices and weather conditions on the entire turf environment.

Healthy Soil Microflora Equals Healthy Turf

The microbial population is an important component of a healthy turf system, which includes a diverse population of beneficial microorganisms in the root zone. Microbial activity is favoured by medium to high temperatures, adequate soil moisture, good soil aeration and an adequate level of organic material to use as a food source. Conversely, saturated soils or overly dry conditions prevent the growth of soil microorganisms. An example of the beneficial effects of soil microbes is seen with 'take-all decline'. There is a decrease in take-all patch after several years of a severe outbreak and it is thought that the cessation of symptoms may be due to an increase in certain bacteria (Pseudomonas sp.) that colonize the fungal mycelium and destroy it.

Repeated use of some fungicides affects the root zone environment and the microbial populations by lowering the soil pH in the top few centimetres. For example, repeated applications of the fungicides benlate, mancozeb, thiram and thiophanate methyl can lower the pH immediately below the thatch/soil interface. This induces thatch production through the elimination of soil microorganisms that break down the organic matter.

Integrated Turf Management

Turf managers today look at the entire system and use all the information they can to make sound management decisions. Many no longer spray fungicides routinely for diseases because of environmental concerns and the high cost of spray materials. They apply fungicides only when they see a disease developing, or when a disease repeatedly appears every year at a particular spot. When this occurs, they will try to determine which management practices promoted the disease and how these practices can be changed.

The first step in Integrated Turf Management is correct diagnosis. More turf managers are making the effort to determine which disease is present. This enables them to select the management practices that are most effective in preventing further spread and damage and to use fungicides wisely. The trend is reflected in the increasing number of turf samples submitted to the B.C. Ministry of Agriculture's Plant Diagnostic Lab, from 22 samples in 1988 to an average of 95 per year since 1990.

Regular tissue testing helps to identify nutrient deficiencies before symptoms develop. Fertility management is challenging on sand-based turfgrass because the nutrient holding capacity is low, however, early correction can prevent plant stress that makes plants more susceptible to disease. For example, the severity of take-all patch can be reduced in soils deficient in phosphorus, zinc or copper when the deficient element is applied. Moderate nitrogen fertilization with balanced potassium and phosphorus will reduce brown patch caused by Rhizoctonia and Pythium root rot severity increases where soil phosphate is deficient. Soil pH can be affected by the various management components. Tests for soil pH are important because turf grows poorly and is more susceptible to nutrient imbalances when the pH is outside of the optimal range. As well, soils with pH 7 or more are conducive to take-all patch. This may occur because the populations of antagonistic microbes are reduced under high pH.

Irrigation is another important component in managing turf diseases. Anaerobic conditions reduce plant vigour and defense mechanisms as well as restrict the activity of beneficial microbes. Water tables trapped above an imperious layer are known as perched water tables and can cause anaerobic conditions even in sand. Wet foliage promotes anthracnose, microdochium (Fusarium/Gerlachia) patch, red thread, pink patch, brown patch and other diseases. These disease can often be reduced by strategically removing trees to improve air circulation and drainage, and irrigating early in the morning to allow moisture to dry during the day.

Thatch removal and aeration are necessary to provide a better environment for plant roots. Where excessive build-up of thatch persists, it may be wise to reduce the use of the fungicides iprodione, benomyl, mancozeb, thiram or thiophanate methyl because they will induce thatch development with repeated use. Anilazine, captan, chlorothalonil and quintozene do not induce thatch development, nor do they increase soil acidity.

Fungicides use must be carefully considered because chemicals applied to control one disease may increase other diseases. For example, benomyl and thiophanate methyl are not toxic to fungi such as Pythium, Typhula, rust, red thread, some Rhizoctonia species and some Helminthosporium species and they have been known to amplify these diseases when used frequently. Frequent use may also lead to the development of resistance. Therefore, it is essential to maintain good records so that fungicides can be rotated where possible.

Integrated turf management practices emphasize managing the whole plant and weighing the value of various practices. For example, turf roots infected by Pythium during cool, wet weather may continue to function under cool and wet conditions, however, these damaged root systems are inadequate to provide sufficient water to plants when the weather becomes warmer and drier. In this situation, it is essential to prevent further plant stress by supplying sufficient water. While it is true that Pythium needs wet conditions to infect roots, in this case it would be more important to adjust the environment to suit the plant's needs during this time.

Making the Transition

A better understanding of the interactions of these management components is needed. With the emphasis on managing the whole plant, many positive changes have occurred. However there are still questions that turf managers want answered. For example, how do you correlate the results of tissue tests with soil tests? How available is phosphorus even if tests of the sand medium indicate high levels? What is the best way to control Pythium root rot? Further research is required to understand pathogen/plant interactions, to understand the effects of fertility in a sand-based system and to learn how current cultural practices impact plant health and vigour. Dr. Brian Holl is conducting research at the Pacific Turfgrass Research Plots to examine the latter two components. I have also started a trial there to determine whether the microbial organisms found in compost amendments will reduce the development of Pythium root rot as they did in studies conducted at Cornell University. As well, we are looking at the species of Pythium involved in root rot in B.C. and the environmental conditions that promote their growth. Researchers in Puyallup, Washington, are examining the role of phosphorus and sulphur fertilization in disease reduction. Results from these research projects, conducted under our climatic conditions, should enable turf managers in B.C. to make better management decisions to reduce fungicide use, while producing healthier turf.

Pest Management Plans in British Columbia

Linda A. Gilkeson, Ph.D. Integrated Pest Management Coordinator, BC Environment

Under the existing pesticide regulatory system in British Columbia, permits are required from the Ministry of Environment, Lands and Parks for all pesticides used on public land and for some uses on private land. Private land uses include forestry and transportation and public utility corridors, such as power line rights-of-way. The permit system is now being revised as part of the new direction taken by the Ministry in 1991 to promote integrated pest management (IPM) and reduce pesticide impacts on the environment. In future, proponents wishing to use pesticides will be required to file pest management plans showing how they intend to manage pest problems on their sites. Plans will include monitoring and evaluation methods, injury and action thresholds and preventative practices as well as pesticide safety methods and a public information plan. Under planned changes to provincial legislation, pest management plans will be required by law and enforceable under the provincial pesticide legislation; this means they may be suspended or revoked if they have not been followed. The pest management plan initiative is expected to:

• Promote IPM and ensure that pesticides are used only in the context of an IPM program.
• Reduce, and eliminate where possible, pesticide impacts on the environment by giving preference to preventative and least-toxic treatments.
• Broaden public awareness of, and involvement in, IPM programs by inviting public input.
• Make more efficient use of administrative and technical efforts currently devoted to the pesticide use permit system.
• Commit major pesticide users to IPM at the upper management level.

During the summer of 1993, potential applicants from forestry and utility companies throughout B.C. as well as people from other interested organizations were asked for their comments on a draft pest management plan document. Their comments have been compiled and will be used in writing a final draft this fall. The response to the initiative has been generally positive and is seen by most proponents as an improvement over the permit system.

Landscape Pest Management Plans

A separate, but related, initiative in B.C. is the development of landscape pest management plans. These will also cover the use of pesticides on public land, but on smaller areas, such as parks and municipal lands, hospital and school ground, etc. that are too small to handle through the permit system. These areas are currently covered by a system of endorsements to pesticide licenses, given by the Pesticide Management Program regional managers. Last year, the Regional Manager in the Vancouver Island Region required applicants for landscape pesticide endorsements to file a pest management plan for each pest category (i.e., broadleaf weeds in turf, insects in ornamental trees, fungi in turf). Applicants were asked for identification and monitoring methods, impact assessment and action level information, descriptions and rationale for chosen treatments and how the program was to be evaluated. Although the first year was primarily educational, plans that do not meet a certain standard in 1994 will be rejected. To develop standards appropriate for landscapes in coastal area of B.C. (where the majority of people live) a working group has been established with 10 representatives from private landscape management companies, school boards and municipal parks department (including full-time IPM coordinators hired by the cities of Victoria and Vancouver). These experts have been charged with developing acceptable IPM standards for each category of pest management. The draft standards for landscape pest management plans are expected to be in place by mid-January, 1994.

Biological Control of Purple Loosestrife

Roy Cranston, Weed Specialist

B. C. Ministry of Agriculture, Fisheries and Food

In 1991, following rigorous host specificity testing, North American federal governments approved the introduction of natural agents to attack purple loosestrife. The three agents approved for release in Canada are a root-feeding weevil (Hylobius transversovittatus) and two leaf-feeding beetles (Galerucella calamariensis and Galerucella pusilla). Only one agent, G. calamariensis, has been released in British Columbia to date. The initial B.C. release took place on June 1, 1993 at the Canadian Wildlife Service property on Westham Island. Subsequent releases were made to Jericho Park in Vancouver, Burnaby Lake, the Vedder wetlands at Chilliwack, Cheam Lake and at the Okanagan Drainage Canal in Penticton. Monitoring to determine survival and impact will occur over the next several years. The other two agents, currently being propagated by the University of Guelph and Agriculture Canada at Lethbridge, will be released to B.C. as stocks become available.

In its native European habitat, purple loosestrife is rapidly controlled by natural insect agents. Once the insects acclimatize and begin reproducing, there is a high probability for successful reduction of British Columbia's increasing purple loosestrife populations.

Pesticide Sales and Use in British Columbia: 1991

The Pesticide Management Program, with funding support from Environment Canada, contracted Norecol Environmental Consultants to compile a comprehensive study of 1991 pesticide use in the province. Results of this study, which was finished this spring, are now available.

Some Highlights from the Study:

• In 1991, British Columbians purchased or used pesticide products containing 274 different active ingredients; the total weight of these active ingredients was 5,039,977 kg.
• Twenty active ingredients accounted for about 90% of the pesticide use, by weight, in the province.
• Anti-microbial chemicals, including wood preservatives, anti-sapstain chemicals and slimicide ingredients were the most-used pesticides (representing 80% of the total).
• When wood treatment chemicals and slimicides are excluded, more than a third (36%) of the total pesticides used were herbicides and just under a third (31%) were insecticides. Fungicides comprised 18%, with all other classes of pesticides combined making up the remaining 15%.
• Agricultural use accounted for 76% of pesticide active ingredients, excluding wood treatments and slimicides. Although several hundred active ingredients were sold, eight active ingredients accounted for more than half of the total weight of pesticides sold for agricultural use. These were insecticidal mineral oil (mainly dormant oil) and herbicidal mineral oil, followed by glyphosate (a herbicide), mancozeb, sulphur, captan, metiram (all fungicides) and ethalfluralin (a herbicide).
• In forestry, the herbicide glyphosate was the most widely used chemical, comprising 87% of the weight of active ingredients applied.

A technical report with a complete summary of results is available.

A New Pest Management Information System

With the assistance of funding from the Agriculture Green Plan, the Pesticide Management Branch and System Services Branch of BC Environment are currently in the process of developing the Integrated Pest Management Information System (IPMIS). This will be a publicly accessible database of information on managing pests (insects, diseases, weeds, rodents, etc.) in B.C., which will emphasize integrated pest management and the use of alternatives to pesticides. IPMIS will contain information on experts, products and sources, bibliographic information as well as complete documents in electronic format.

The contract to develop the prototype application has been awarded to The Coopers & Lybrand Consulting Group. Plans for this fiscal year are to develop and test the prototype application by early February, purchase and install hardware components and enter as much information as possible into the system. The system should be available to Ministry staff by spring 1994 to assist them in providing information on IPM. Sometime during next year, it is planned to make the information in the system available to the public through the Internet computer network. Anyone with a modem would be able to use the information system directly or, if they do not have a computer access, they would be able to obtain information from government staff who do have access to the information system; this information would then be provided in a convenient format such as a printed copy or on a computer disk.

New Products

Flame Weeder

The Primus weed torch is a hand-held flame weeder for use around gardens, lawns and walkways. The propane fueled flamer is used to apply heat to weeds and shrivel the foliage; also used to remove ice from walkways. Sold by mail order or at the Vancouver store; cost $89.00 (shipping additional).

Mail order catalogue available from:Local Store:

Lee Valley Tools, Ltd.Lee Valley Tools, Ltd.

P.O. Box 6295, Stn. J. Ottawa, Ont. K2A 1T41098 S.W. Marine Dr.

Tel: 1-800-267-8767Vancouver, B.C.

Fax: 1-800-668-1807Tel: (604) 261-2262

Flea Trap

The Flea Killer is an new version of the flea light trap designed to catch fleas in homes. It has a small light bulb to attract the fleas, which are caught on a replaceable sticky pad. Available at some pet stores and garden centres or directly from:

BioCare Products Ltd.

98-C Burnside Road West

Victoria, B.C. V9A 1B5

Tel: (604) 383-1903 or 1-800-668 TRAP

Fax: (604) 383-6775

Fatty Acid Herbicide

DowElanco has the marketing rights in Canada to Spectrumreg., the commercial product containing the fatty acid herbicide originally developed by Safer's (TopGun TM is the domestic product). Results are reported to be visible the same day; treated areas can be replanted in 3 days. Because it has no systemic or translocation effect it can be used up to the base of trees.

Available from:

Westgro Sales, Progress Way, Delta, B.C.

Services

Weed Burner

Western Weed Control, Ltd., is offering a weed burning service for vegetation control. It is a tractor-driven unit with propane powered burners for use in areas such as sports fields, road shoulders, traffic islands and sidewalks and parking areas.

For more information:

Western Weed Control (1980) Ltd.

PO Box 36 Station Main, Maple Ridge, BC, V2X 7E9

Phone: Toll Free 1-888-856-9333, Tel: (604) 462-0637, Fax: (604) 462-924